CircHIPK3 regulates cardiac fibroblast proliferation, migration and phenotypic switching through the miR-152-3p/TGF-β2 axis under hypoxia

Abstract

Background The occurrence of pathological cardiac fibrosis is attributed to tissue hypoxia. Circular RNAs play significant regulatory roles in multiple cardiovascular diseases and are involved in the regulation of physiological and pathophysiological processes. CircHIPK3 has been identified as the one of the most crucial regulators in cardiac fibrosis. However, the mechanisms by which circHIPK3 regulates cardiac fibrosis under hypoxia remain unclear. Our study aimed to determine circHIPK3 expression in cardiac fibroblasts (CFs) and investigate the functions of circHIPK3 in hypoxia environment. Methods The expression level of circHIPK3 in CFs under hypoxia (1% O2) was analyzed by qRT-PCR. The role of circHIPK3 on the proliferation and migration of CFs were determined by EdU, cell wound scratch assay and cell cycle. The expression of proteins associated with phenotypic transformation in CFs in vitro was examined by immunofluorescence assay and western blot. Bioinformatics analysis, dual luciferase activity assay and RNA fluorescent in situ hybridization assay revealed that miR-152-3p was identified as a target of circHIPK3 and that TGF-β2 was targeted by miR-152-3p. Results CircHIPK3 expression was significantly upregulated in CFs in a hypoxic environment. In vitro, overexpressing circHIPK3 obviously promoted CF proliferation, migration and phenotypic changes under hypoxia, but those processes were suppressed by circHIPK3 silencing. CircHIPK3 acted as an endogenous miR-152-3p sponge and miR-152-3p aggravated circHIPK3 silencing induced inhibition of CF proliferation, migration, phenotypic transformation and TGF-β2 expression in vitro. In summary, circHIPK3 plays a pivotal role in the development of cardiac fibrosis by targeting the miR-152-3p/TGF-β2 axis. Conclusions These findings demonstrated that circHIPK3 acted as a miR-152-3p sponge to regulate CF proliferation, migration and phenotypic transformation through TGF-β2, revealing that modulation of circHIPK3 expression may represent a potential target to promote the transition of hypoxia-induced CFs to myofibroblasts.

Circle the Cardiac Remodeling With circRNAs

“…Similarly, another study showed circHIPK3 induced cardiac fibrosis through a circHIPK3/miR-29b-3p/Col1a1/Col3a1 signaling cascade in mouse diabetic cardiomyopathy model (86). Interestingly, circHIPK3 modulates CFs function in a hypoxia condition in a similar sponge manner, but through a different signaling cascade, the circHIPK3/miR-152-3p/TGF-β2 axis (87). Therefore, circHIPK3 is likely to be an important upstream node of the miRNA-mediated posttranscriptional gene regulation network in cardiac fibrosis.…”

CircHIPK3 Plays Vital Roles in Cardiovascular Disease

“…CircHIPK3 is widely expressed in various tissues, such as the heart, lung and colon ( 26 ), consistent with its roles in CVD ( 32 , 43 – 46 ), cancers ( 12 , 27 , 28 , 47 ), and neuronal diseases ( 48 , 49 ). CircHIPK3 mainly functions through sponging miRNAs ( 32 , 34 , 43 , 44 , 50 ). CircHIPK3 can be wrapped in exosomes to facilitate cell-to-cell communication ( 43 , 51 – 53 ).…”

“…Then, numerous non-beating myofibroblasts replace the functional myocardium, resulting in myocardial dysfunction ( 99 ). CircHIPK3 has been identified to be abundantly expressed in CFs and to function in myocardial fibrosis ( 34 , 44 ).…”

“…Liu et al illuminated the role of circHIPK3 in cardiac fibrosis under hypoxia ( 34 ). The expression of circHIPK3 was significantly increased in CFs treated with hypoxia.…”

LncRNA CASC19 accelerates chondrocytes apoptosis and proinflammatory cytokine production to exacerbate osteoarthritis development through regulating the miR-152-3p/DDX6 axis

“…Furthermore, miR-152-3p targets CDK8 to regulate hepatic carcinogenesis [ 22 ]. CircHIPK3 sponges miR-152-3p to release TGF-β2, thus promoting cardiac fibrosis under hypoxia by regulating fibroblast proliferation and phenotypic switching [ 23 ]. Additionally, miR-152 regulates TCF-4 pathway in OA rats to weaken chondrocyte apoptosis and cartilage degeneration [ 24 ].…”